The present invention is directed to dispersions of lamellar pigment particles that are useful in forming coating compositions, i.e. metal pigment-containing paints, mica-containing paints and others. Such paints are used, for example, for coatings in the automotive, plastics, can coatings, and coil coatings industries, and for forming metallic coatings for roofs and other similar structural surfaces. The particles generally are used in a flake like form.
Typically, in order to avoid stability problems and decrease shipping costs, the lamellar pigment particles for use in such coating compositions have been provided to the customer (i.e. a paint manufacturer or ultimate end user) in the form of a highly concentrated paste. The paste is then mixed with a suitable vehicle for forming the final coating composition.
However, in practice it has been difficult for the paint manufacturer or end user to form a paint with the pigment paste, especially with the finer grade pigment pastes. It has been time-consuming and relatively labor intensive to ensure that the paste is completely mixed with the paint vehicle. In addition, the difficulty in mixing the paste with the vehicle has resulted in the use of relatively severe mixing techniques that can damage the metal flakes, e.g. by bending, curling or tearing. Generally, the paste will be added to a tank containing the paint vehicle or some component thereof. As the paste is added, the mixture is stirred with a propeller or Cowles blade or the like. Such procedures are not effective in separating the particles in the paste and can result in the damage to the particles discussed above, and also requires additional processing such as filtration to remove undispersed particles. This causes problems such as batch-to-batch inconsistency and less desirable aesthetic properties. It also has been found that the paste can be difficult to remove from bulk containers such as drums.